“…The stability of the above scheme, denoted in the following as J‐E(1), was studied in Prokopidis and Zografopoulos
8 and a similar method can be formulated with less restricted stability criterion
as already proposed in Ramadan
19 and Prokopidis and Zografopoulos,
20 denoted here as J‐E(2). The relative numerical permittivity for this scheme can be obtained similarly and it is given by () as of the proposed scheme.…”